Merge tag 'for-5.9/block-20200802' of git://git.kernel.dk/linux-block

Pull core block updates from Jens Axboe:
 "Good amount of cleanups and tech debt removals in here, and as a
  result, the diffstat shows a nice net reduction in code.

   - Softirq completion cleanups (Christoph)

   - Stop using ->queuedata (Christoph)

   - Cleanup bd claiming (Christoph)

   - Use check_events, moving away from the legacy media change
     (Christoph)

   - Use inode i_blkbits consistently (Christoph)

   - Remove old unused writeback congestion bits (Christoph)

   - Cleanup/unify submission path (Christoph)

   - Use bio_uninit consistently, instead of bio_disassociate_blkg
     (Christoph)

   - sbitmap cleared bits handling (John)

   - Request merging blktrace event addition (Jan)

   - sysfs add/remove race fixes (Luis)

   - blk-mq tag fixes/optimizations (Ming)

   - Duplicate words in comments (Randy)

   - Flush deferral cleanup (Yufen)

   - IO context locking/retry fixes (John)

   - struct_size() usage (Gustavo)

   - blk-iocost fixes (Chengming)

   - blk-cgroup IO stats fixes (Boris)

   - Various little fixes"

* tag 'for-5.9/block-20200802' of git://git.kernel.dk/linux-block: (135 commits)
  block: blk-timeout: delete duplicated word
  block: blk-mq-sched: delete duplicated word
  block: blk-mq: delete duplicated word
  block: genhd: delete duplicated words
  block: elevator: delete duplicated word and fix typos
  block: bio: delete duplicated words
  block: bfq-iosched: fix duplicated word
  iocost_monitor: start from the oldest usage index
  iocost: Fix check condition of iocg abs_vdebt
  block: Remove callback typedefs for blk_mq_ops
  block: Use non _rcu version of list functions for tag_set_list
  blk-cgroup: show global disk stats in root cgroup io.stat
  blk-cgroup: make iostat functions visible to stat printing
  block: improve discard bio alignment in __blkdev_issue_discard()
  block: change REQ_OP_ZONE_RESET and REQ_OP_ZONE_RESET_ALL to be odd numbers
  block: defer flush request no matter whether we have elevator
  block: make blk_timeout_init() static
  block: remove retry loop in ioc_release_fn()
  block: remove unnecessary ioc nested locking
  block: integrate bd_start_claiming into __blkdev_get
  ...

1 files changed, 28 insertions, 3 deletions

diff --git a/block/blk-lib.c b/block/blk-lib.c
index 5f2c429d4378..019e09bb9c0e 100644
--- a/block/blk-lib.c
+++ b/block/blk-lib.c
@@ -29,7 +29,7 @@ int __blkdev_issue_discard(struct block_device *bdev, sector_t sector,
 	struct request_queue *q = bdev_get_queue(bdev);
 	struct bio *bio = *biop;
 	unsigned int op;
-	sector_t bs_mask;
+	sector_t bs_mask, part_offset = 0;
 
 	if (!q)
 		return -ENXIO;
@@ -54,9 +54,34 @@ int __blkdev_issue_discard(struct block_device *bdev, sector_t sector,
 	if (!nr_sects)
 		return -EINVAL;
 
+	/* In case the discard request is in a partition */
+	if (bdev->bd_partno)
+		part_offset = bdev->bd_part->start_sect;
+
 	while (nr_sects) {
-		sector_t req_sects = min_t(sector_t, nr_sects,
-				bio_allowed_max_sectors(q));
+		sector_t granularity_aligned_lba, req_sects;
+		sector_t sector_mapped = sector + part_offset;
+
+		granularity_aligned_lba = round_up(sector_mapped,
+				q->limits.discard_granularity >> SECTOR_SHIFT);
+
+		/*
+		 * Check whether the discard bio starts at a discard_granularity
+		 * aligned LBA,
+		 * - If no: set (granularity_aligned_lba - sector_mapped) to
+		 *   bi_size of the first split bio, then the second bio will
+		 *   start at a discard_granularity aligned LBA on the device.
+		 * - If yes: use bio_aligned_discard_max_sectors() as the max
+		 *   possible bi_size of the first split bio. Then when this bio
+		 *   is split in device drive, the split ones are very probably
+		 *   to be aligned to discard_granularity of the device's queue.
+		 */
+		if (granularity_aligned_lba == sector_mapped)
+			req_sects = min_t(sector_t, nr_sects,
+					  bio_aligned_discard_max_sectors(q));
+		else
+			req_sects = min_t(sector_t, nr_sects,
+					  granularity_aligned_lba - sector_mapped);
 
 		WARN_ON_ONCE((req_sects << 9) > UINT_MAX);